Packaging technology for electronic circuits is becoming a more and more complex field. The reason for this is on the one hand the rising technical requirements placed on miniaturization in microtechnologies and on the other hand the enormous pressure to provide for a technology that is as cost-effective as possible and yet reliable. One possibility in this regard is offered by flip-chip technology. In flip-chip technology, un-housed semiconductor chips are mounted directly on a substrate by a simultaneous contacting process. This ensures the shortest wiring paths. Typically, the semiconductor chip is positioned over a substrate with its active side, i.e., the side bearing the components, facing down and is contacted by a soldering process or a bonding process. For this purpose, one of the bonding partners —the semiconductor chip or the substrate —has contacting protuberances, which in the case of a soldering process are also called “solder bumps” or simply “bumps.” The bumps melt during the soldering process and thus connect the semiconductor chip electrically and mechanically with the substrate.
The bumps are usually attached peripherally or on two opposite edge regions of the semiconductor chip. Following the soldering process, the semiconductor chip is thereby connected to the substrate at least on both sides—more precisely on opposite edge regions. This procedure, however, is unfavorable particularly in a semiconductor chip having micromechanical sensor elements. In temperature changes, different thermal expansions cause the semiconductor chip and the substrate to shift relative to each other, producing mechanical stresses. These stresses affect the measured values of the sensor elements, which are often beyond what can be tolerated.
A possibility for preventing or reducing such stresses is to arrange all bumps and thus all electrical and mechanical contacts only in one edge region. Such an arrangement is described, for example, in German patent document DE 102004011203.7.
The production of unilaterally attached semiconductor chips is not without problems, however. For a reliable anchorage before and during the soldering process, a holding device is required which holds the semiconductor chip for the soldering process. This holding device can either be removed following the soldering process or can remain on the semiconductor chip. In the first case, an additional process with associated costs is in turn necessary; in the second case, again forces affecting the sensor elements act on the semiconductor chip in the operating state.
Thus there is a need for a method for mounting unilaterally attached semiconductor chips, which method dispenses with a removal of the holding device required for anchoring the semiconductor chips.